Manufacture of fluorohydrocarbons



Patented May 31,1938

UNITED s'rA'ras MANUFACTURE OF FLUOROHYDBO- CARBONB Julius 861i.Leverkusen-I. a. Work, as t im! 01. G. Farbonindustrle or r cobalt,Frankiort-on-the-Main, Germany I Nam-swing. Application February 12,rose.

Claims; (Cl. 280-186) This invention relates to the manufacture offiuoro-hydrocarbons.

The object of my present invention is to cause hydrogen fluoride or anaqueous solution thereof 5 to react upon acetylene in the presence ofmercuric compounds and/or active carbons. Asmercuric compounds there maybe used, for instance, mercuric oxide, chloride or fluoride. In somecases it is preferable not to use the mercury 0 catalysts as such, butto support them upon carriers such, for instance, as activated charcoalswhich, moreover, have a catalytic eflect by themselves. The reaction maybe carried out, for instance, by merely passing a gaseous mixture ofhydrogen fluoride and acetylene over the catalyst. The reaction sets inat ordinary temperature and is exothermic, so that, owing to the heatliberated, the temperature of the catalyst rises spontaneously, thusaccelerating the reaction velocity. Of course, it is also possibleto-start the reaction at elevated temperatures. Preferably the gasespassing over the catalyst are caused to circulate and the resultingfiuorinated hydrocarbons are removed from the gases as far as possibleon each return of the gases to the reaction vessel. The reactiontemperature can be regulated by varying the quantity and the compositionof the circulating gases. It is also possible to regulate thetemperature by mixing the reaction gases with indifferent gases, thepercentage of which, due tothe continuous removal of the reactionproducts, increases during the reaction. The preferred form of myinvention is to work at a temperature below about 0.,

more particularly, below about 30 C. The hydrofluoric acid can beemployed in form of an aqueous solution or preferably in a water freestate.

composition of the gas mixture and on the reaction conditions; in caseacetylene is employed in excess vinyl fluoride is predominant; in casethe hydrofluoric acid is employed in excess the resulting productchiefly consists of difluorethanes. The components can be separated byfractional distillation either at ordinary temperature and increasedpressure or at lower temperatures and atmospheric pressure,

The products thus obtained are suitable for various purposes, forinstance, they are excellent cooling media for refrigeration machines asthey are favorably distinguished from the corresponding chlorinecompounds employed for this purpose by their non-poisonous nature. Thenew products are further particularly valuable for the manufacture ofother fiuorinated hydrocarbons and polymerization products.

The following example illustrates the invention without, however,restricting it thereto:

The reaction products formed depend on the Example 1 litre of granulatedactivated charcoal is stirred with an aqueous suspension of 50 grams ofmercuric oxide and-dried. The catalyst thus obtained is brought into aniron vessel. a mixture of gases containing acetylene and hydrogenfluoride is then circulated through the catalyst, whereby thetemperature is maintained at about 20 to 40 C. The ture of the hydrogenfluoride may be effected in various ways, for instance by pumping thecirculating gases before entering the catalyst through an iron cylindercontaining anhydrous hydrogen fluoride at 0 G. A suitable amount ofacetylene is admixed before reaching the catalyst, and alter leaving it,a corresponding amount of gases is removed, from which the fluorinatedhydrocarbons are sep aratecl. It is also possible to remove the products directly from the circulating gases, for instance, by means ofsuitable solvents.

The physical constants of the products in question are the following: v

Vinylfluoride Pressure 10 mm. Hg 262.8 mm. Hg 480.3 mm. Hg l si? m.3510:: heric ressure Bollingi olnt,7c mm.%g. I

Critical temperature C 417.5 Melting point do l6t.5 Specificgravity-+265 C.. =ilt6i5 Specific gravityl l9 C-.. =il.998 Specificgravity-722 Cu--- :Odfit 1,1-difla0rethane Pressure 32 mm. Hg 444.7 mm.Hg 1 :5 a 5210s horic ressure Boiling" point, wgmm lg.

Critical temperature -C +1075 Melting point 'do -l.l.7 Specificgravity-78,8 C =l.l2ii Specific gravity 0 =0.958 Specific gravity+19\-C=ll.9i2 Specific gravity-26 C =1.030

In Handbuch der organischen Chemi e by Beilstein IV edition, volume 1,page 186, a fluorethylene of a boiling point of 5l C. is described. Thisfigure is obviously due to a mistake.

the hydrofluoric acid is employed in a water tree state.

4. The process which comprises causing a mixture oi gaseous hydrofluoricacid and acetylene to circulate through a catalyst selected from thegroup consisting oi mercuric oxide and mercuric halides precipitated ona carrier, at such a rate as to prevent a rise 01' the reactiontemperature above about 40 C.

5; The process which comprises causing a mixture of gaseous hydrofluoricacid and acetylene to circulate through a catalyst selected from thegroup consisting of mercuric oxide and mercuric halides, precipitated onactive carbon, at such a rate as to prevent a rise of the reactiontemperature above about 40 C.

JULIUS $61.1

